1. The Field of the Invention
This invention relates generally to the field of electrical connector systems for electrical components. In particular, embodiments of the present invention relate to a latching system that is particularly useful for use with low profile, user-removable, electronic modules that interface with a port of a host device. For example, embodiments of the present invention may find particular use with opto-electronic transceiver modules used to interface a host device with an optical communications network.
2. The Relevant Technology
Fiber optics are increasingly used for transmitting voice and data signals. As a transmission medium, light provides a number of advantages over traditional electrical communication techniques. For example, light signals allow for extremely high transmission rates and very high bandwidth capabilities. Also, light signals are resistant to electro-magnetic interferences that would otherwise interfere with electrical signals. Light also provides a more secure signal because it doesn""t allow portions of the signal to escape from the fiber optic cable as can occur with electrical signals in wire-based systems. Light also can be conducted over greater distances without the signal loss typically associated with electrical signals on copper wire.
While optical communications provide a number of advantages, the use of light as a transmission medium presents a number of implementation challenges. In particular, the data carried by light signal must be converted to an electrical format when received by a device, such as a network switch. Conversely, when data is transmitted to the optical network, it must be converted from an electronic signal to a light signal. A number of protocols define the conversion of electrical signals to optical signals and transmission of those optical, including the ANSI Fibre Channel (FC) protocol. The FC protocol is typically implemented using a transceiver module at both ends of a fiber optic cable. Each transceiver module typically contains a laser transmitter circuit capable of converting electrical signals to optical signals, and an optical receiver capable of converting received optical signals back into electrical signals.
Typically, a transceiver module is electrically interfaced with a host devicexe2x80x94such as a host computer, switching hub, network router, switch box, computer I/O and the likexe2x80x94via a compatible connection port. Moreover, in some applications it is desirable to miniaturize the physical size of the transceiver module to increase the port density, i.e., and therefore accommodate a higher number of network connections within a given physical space. In addition, in many applications, it is desirable for the module to be hot-pluggable, which permits the module to be inserted and removed from the host system without removing electrical power. To accomplish many of these objectives, international and industry standards have been adopted that define the physical size and shape of optical transceiver modules to insure compatibility between different manufacturers. For example, in 1998, a group of optical manufacturers developed a set of standards for optical transceiver modules called the Small Form-factor Pluggable (xe2x80x9cSFPxe2x80x9d) Transceiver MultiSource Agreement (xe2x80x9cMSAxe2x80x9d). In addition to the details of the electrical interface, this standard defines the physical size and shape for the SFP transceiver modules, and the corresponding host port, so as to insure interoperability between different manufacturers"" products. The standard also specifies that the module be hot-pluggable. To do so, the standard specifies that a user provide a minimum amount of space between host ports, so that transceiver modules can be individually accessed and removed from the host device without disturbing the adjacent modules and/or cable connections.
While such standards may recommend that there be a minimum distance between adjacent ports, there is often a desire to provide configurations having a higher port density. However, providing a high port density can be at odds with the ability to provide a module that complies with existing standardsxe2x80x94i.e., that has a small form-factor and is hot-pluggable. In particular, previously existing module designs present a size and profile that mandates that a specific minimum amount of space be provided between host ports so that individual modules can be accessed and removed without disturbing an adjacent module and/or an adjacent fiber cable. Such modules either cannot be used in a device having a high port density (due to the space requirements), or, if used in such an environment, require the use of a special extraction tool to allow for access and retrieval of a module without disturbing adjacent modules and/or cables. Use of an extraction tool is often not desirable because it raises costs, can be misplaced, and may not be compatible with other module designs.
Therefore, there is a need for a module, such as an optical transceiver module, that utilizes a latching scheme that allows the module to maintain its small form factor and that still complies with existing standards. At the same time, the latching scheme should allow the module to be easily inserted and extracted from a port without the need for a special extraction tool. Moreover, extraction should be possible in a manner that does not disturb the communications link of adjacent modules, i.e., extraction should be achieved without inadvertently removing an adjacent module and/or fiber cable, even in a host having high port density. Such a module would allow host systems to provide a higher packing density, and yet allow the use of small form factor transceiver modules that comply with existing standards,
These and other problems in the prior art are addressed by embodiments of the present invention, which relates to an electronic, pluggable module that is equipped with a unique latching mechanism. In an illustrated embodiment, the module is an opto-electronic transceiver module, typically used to interface an optical transmission cable medium to a host device, such as a network switch, hub, router, computer or the like.
In one preferred embodiment, the module is formed as a small form-factor pluggable (xe2x80x9cSFPxe2x80x9d) device in accordance with existing industry standards. Moreover, the module is capable of being operatively received within a compatible port provided by the host device. It will be appreciated that while preferred embodiments are illustrated and described as an opto-electronic transceiver module, the present invention is not limited to that particular environment. Indeed, teachings of the present invention could also be utilized in any type of pluggable electronic module.
In an exemplary embodiment, the module includes a base portion that supports a printed circuit board (PCB) upon which is disposed the electronics needed for the functionality of the module. In addition, the PCB has an edge connector formed at one end that is capable of electrically interfacing with the host device when the module is operatively received within the device port. Also disposed on one end of the base portion is at least one receptacle capable of physically receiving and interfacing with a corresponding optical fiber connector, which in turn is connected to a fiber optic cable. In a preferred embodiment, an outer housing encloses at least a portion of the base and the PCB to protect the electronic and optical components from dust and the like. Moreover, the housing defines an outer periphery that conforms in size and shape to the corresponding host port. In one preferred embodiment, the size and shape correspond to specifications defined by the MSA standard. Of course, other shapes and sizes could be used.
In illustrated embodiments, the module includes an integrated latching mechanism that provides several preferred functions. In particular, the latch mechanism provides the ability to releasably secure the transceiver module within the host port. Moreover, the latch mechanism can be implemented within a transceiver module having a SFP package, and can be done so with mechanical dimensions that do not violate industry standards. The latch mechanism permits easy extraction and insertion of the module by a user, even when it is used in a host device having a high-density port configurationxe2x80x94both laterally and vertically. Further, extraction can be accomplished without the use of a specialized extraction tool, and without disturbing adjacent modules and/or cables.
In one preferred embodiment, the latch mechanism is operated by way of a moveable bail lever. The bail is moveable between two positions, which in turn dictate the position of a locking pin. When placed in a latched position, the locking pin extends from the module and engages with a corresponding recess within the host port. In this position, the module is latched and secured within the port. When the bail is moved to an unlatched position, the locking pin is disengaged from the locking recess, which permits the module to be extracted from the port.
In the exemplary embodiment, movement of the locking pin by way of the bail is accomplished with a cam portion that is integrated with the bail lever. Rotation of the bail causes manipulation of the cam, which in turn operates against a cam follower surface formed on a pivot block which carries the locking pin. When in the latched position, the cam is disengaged from the cam follower surface, and a biasing means formed on the housing urges the pivot block to rotate the locking pin into the latched position. In contrast, in the unlatched position, the cam forces the pivot block to rotate the locking pin so that it is disengaged from the locking recess.
In addition to manipulating the latching mechanism, the bail also provides a lever for removing the module from the port. Thus, when positioned in the unlatched position, the bail extends outwardly to the front of the module, so that a pulling force results in the removal of the module. Importantly, in preferred embodiments the bail provides a handhold portion, so that this removal can be accomplished with a user""s finger, and doesn""t require the use of a specialized extraction tool. Moreover, since the bail is positioned in the front of the module, the module can be removed without disturbing adjacent modules and without disturbing adjacent cablesxe2x80x94even when used in a host device having a high port density.
In a preferred embodiment, the shape of the bail and the rest of the latching mechanism are integrated within the module so as to not violate the requisite form factor. Moreover, the shape of the bail is such that when the fiber cable connector is positioned within the receptacle, the bail cannot be moved to the unlatched position. This prevents accidental removal of the module from the port, such as may otherwise occur when the cable or plug are inadvertently pulled.
The foregoing, together with other features and advantages of the present invention, will become more apparent when referred to the following specification, claims and accompanying drawings.